1. Field of the Invention
The present invention is directed to a process and an apparatus for deflecting the direction of a plurality of light beams in a controllable fashion in particular for a wide-band optical data switching system. The process and apparatus utilizes acousto-optic light deflectors which can deflect an oncoming light beam in at least 10.sup.4 discrete directions of deflection.
2. Prior Art
On account of their simplicity, acousto-optic light deflectors can be used advantageously for many applications. These applications include optical data transmission systems, optical storage systems, display devices, and optical printers.
An optical beam can be optionally deflected with the acousto-optic light deflector within microseconds into one of 10.sup.3 to 10.sup.5 discrete directions of deflection. Known acousto-optic light deflectors were constructed so that a sound wave would advance therethrough and be removed from the unit and the advancing sound waves deflect a light beam, for example a laser beam, so that the switching time between two arbitrary beam directions is governed by the transit time of the sound waves through the cross section of the light beam. Thus typical acousto-optic light deflectors have aa switching time between 1 and 10 .mu.s.
In addition to crystals such as iodic acid, lead molybdate and paratellurite, other suitable deflecting media are glass bodies which have a high index of refraction such as flint glass. In order to achieve a technically useful efficiency of more than 50%, an electric control signal for creating advancing sound waves in the glass bodies, for example, will require a power of 2 to 10 watts.
If a deflector matrix is to be constructed of 10.sup.3 to 10.sup.4 acousto-optic light deflectors which matrix, for example, would be required in either a wide-band optical data switching system or a holographic data storage system, the high driving power, which is required for each individual deflector, means that the cost for constructing the matrix becomes unacceptably high. Furthermore, since the electrical power requirement for each deflector generally exceeds more than 2 watts, it is not possible to use inexpensive, integrated or printed circuits for the electric control system.